Autoinjectors

Abstract

An autoinjector includes front and rear separable housing parts 10, 12 . These are connected by a rotary coupling action such as by bayonet coupling and the relative rotation action turns a needle shield 20 from a locked position in which it is both locked against longitudinal movement and acts as a shutter obscuring the contents of the syringe to an open position where the contents of the syringe are visible and the shield portion is freed for longitudinal movement. Connecting and securing the rear portion 12 on the front portion 11 therefore unlocks the needle shield 20 for operation. On completion of an injection, uncoupling of the front and rear portions returns the needle shield 20 to its locked position so the front portion may be disposed of safely.

The invention claimed is: 
     
       1. An autoinjector, comprising:
 front ( 10 ) and rear ( 12 ) separable housing portions connectable and disconnectable by a coupling action, 
 the rear housing portion containing a drive mechanism ( 54 ), and 
 the front housing portion being adapted in use to receive a syringe having a needle, 
 the front housing portion including a needle shield portion movable between an extended position in which the needle shield shields the needle of the syringe in use, and a retracted position in which the needle of the syringe is exposed; and 
 a locking arrangement configured to lock said needle shield against retraction movement and which is locked and unlocked automatically during or as a result of the coupling action and reversal thereof as the housing portions are connected and disconnected, such that the needle shield is unlocked in an unlocked mode when said front and rear housing portions are connected to each other and locked in a locked mode when said housing portions are disconnected. 
 
     
     
       2. The autoinjector according to  claim 1 , wherein said locking arrangement comprises complementary locking surfaces ( 26 ,  28 ,  30 ) disposed on the needle shield portion ( 20 ) and the front housing portion ( 14 ), respectively. 
     
     
       3. The autoinjector according to  claim 2 , wherein said shield portion ( 20 ) is locked by a relative angular movement. 
     
     
       4. The autoinjector according to  claim 3 , wherein said complementary surfaces include an internal projection ( 30 ) on said front housing portion and a complementary groove on said shield portion, the groove having a rearward circumferential portion ( 26 ) corresponding to the locked mode and, extending therefrom, an axial portion ( 28 ) allowing relative longitudinal movement. 
     
     
       5. The autoinjector according to  claim 4 , wherein said front and rear housing portions are connected by a rotary coupling action, and said needle shield has a rearward connection interface for being engaged by a complementary forward connection interface on said rear housing portion, whereby coupling said front and rear housing portions causes said needle shield to rotate to become unlocked. 
     
     
       6. The autoinjector according to  claim 5 , wherein said forward and rearward connection interfaces comprise longitudinally engageable non-circular male ( 58 ) and female ( 44 ) plug and socket portions. 
     
     
       7. The autoinjector according to  claim 3 , wherein said front and rear housing portions are connected by a rotary coupling action, and said needle shield has a rearward connection interface for being engaged by a complementary forward connection interface on said rear housing portion, whereby coupling said front and rear housing portions causes said needle shield to rotate to become unlocked. 
     
     
       8. The autoinjector according to  claim 7 , wherein said forward and rearward connection interfaces comprise longitudinally engageable non-circular male ( 58 ) and female ( 44 ) plug and socket portions. 
     
     
       9. The autoinjector according to  claim 1 , wherein, in use, the barrel of the syringe is visible through aligned apertures ( 18 ,  32 ,  42 ) in two or more of the front housing portion, the needle shield ( 20 ), and a syringe carrier ( 34 ) when the shield is in the unlocked position, at least one of the apertures moving out of alignment when the shield is locked so the syringe is no longer visible. 
     
     
       10. The autoinjector according to  claim 1 , wherein said shield portion ( 20 ) is locked by a relative angular movement. 
     
     
       11. The autoinjector according to  claim 10 , wherein said front and rear housing portions are connected by a rotary coupling action, and said needle shield has a rearward connection interface for being engaged by a complementary forward connection interface on said rear housing portion, whereby coupling said front and rear housing portions causes said needle shield to rotate to become unlocked. 
     
     
       12. The autoinjector according to  claim 11 , wherein said forward and rearward connection interfaces comprise longitudinally engageable non-circular male ( 58 ) and female ( 44 ) plug and socket portions. 
     
     
       13. An autoinjector, comprising:
 front ( 10 ) and rear ( 12 ) separable housing portions connectable and disconnectable by a coupling action, 
 the rear housing portion comprising a drive mechanism ( 54 ), and 
 the front housing portion being adapted in use to receive a syringe having a needle, and including an inspection window ( 18 ) through which the contents of the syringe may be viewed, 
 the front housing portion also including a shutter arrangement movable between an open position and a closed position, the shutter arrangement being opened when said housing portions are connected and being closed when said portions are disconnected. 
 
     
     
       14. An autoinjector, comprising:
 front and rear separable housing portions configured to be reversibly coupled together, 
 the front housing portion being adapted in use to receive a syringe having a needle, and 
 the rear housing portion containing a drive mechanism that, in use, drives the syringe, 
 the front housing portion including a retractable needle shield movable between an extended position in which the needle shield shields the needle of the syringe, and a retracted position in which the needle of the syringe is exposed; and 
 a locking arrangement that, in a first mode, permits a retraction movement of the needle shield from the extended position to the retracted position and, in a second mode, locks said needle shield against retracting from the extended position to the retracted position, 
 said locking arrangement automatically assuming the first mode upon the front and rear housing portions being coupled together, and automatically assuming the second mode upon the front and rear housing portions being separated from each other in a decoupling action. 
 
     
     
       15. The autoinjector according to  claim 14 , wherein the front housing portion also includes an inspection window through which, in use, the contents of the syringe are viewable. 
     
     
       16. The autoinjector according to  claim 15 , wherein the rear housing portion comprises a bayonet coupling interface complementary to a corresponding bayonet coupling interface on the front housing portion. 
     
     
       17. The autoinjector according to  claim 14 ,
 wherein said front and rear housing portions are coupled to each other by way of a rotary coupling action where the front housing portion is caused to rotate relative to the rear housing portion, and 
 wherein said needle shield of said front housing portion is connected to a rearward connection interface that, upon said rotary coupling action for coupling the front and rear housing portions together, engages with a complementary forward connection interface on said rear housing portion and rotates said needle shield into an unlocked position free to move from the extended position to the retracted position. 
 
     
     
       18. The autoinjector according to  claim 17 , wherein the front housing portion also includes an inspection window through which, in use, the contents of the syringe are viewable. 
     
     
       19. The autoinjector according to  claim 17 , wherein the rear housing portion comprises a bayonet coupling interface complementary to a corresponding bayonet coupling interface on the front housing portion.